Highly sensitive and quantitative detection of a minute amount of a substance to be detected such as protein and DNA in laboratory tests makes it possible to perform treatment by quickly determining the patient's condition. In view of this, the analysis method and the analysis device which can quantitatively detect a minute amount of a substance to be detected with high sensitivity are demanded.
Surface plasmon-field enhanced fluorescence spectroscopy (hereinafter abbreviated as “SPFS”) is known as a method which can detect a substance to be detected with high sensitivity (see, for example, PTLS 1 and 2).
PTLS 1 and 2 disclose an analysis method and an analysis device that utilize SPFS. In the analysis method and the analysis device, a sensor chip including a prism formed of a dielectric, a metal film formed on one surface of the prism, a capturing body (for example antibody) fixed on the metal film is used. When a sample containing a substance to be detected is provided on the metal film, the substance to be detected is captured by the capturing body (primary reaction). The substance to be detected thus captured is further labeled by a fluorescence material (secondary reaction). In this state, when the prism is irradiated with excitation light through the metal film at an angle at which surface plasmon resonance is caused, localized-field light can be generated on the surface of the metal film. With this localized-field light, the fluorescence material for labelling the captured substance to be detected on the metal film is selectively excited, and fluorescence emitted from the fluorescence material is observed. In the analysis method and the analysis device, the fluorescence is detected to detect the presence or the amount of the substance to be detected.
In such analysis methods and analysis devices utilizing SPFS, it is necessary to use highly sensitive light sensors such as a photomultiplier tube (PMT) and an avalanche photodiode (APD) to quantitatively detect weak fluorescence. An excitation light cutting filter that blocks excitation light and allows fluorescence to transmit therethrough is provided on the front of the light sensors.